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WESLACO, Texas — The four-county Rio Grande Valley region may be one of the unhealthiest areas in America, with the nation’s highest rates for cervical cancer and overweight children, according to a study released Wednesday.

Rates of women who are opting for preventive mastectomies, such as Angeline Jolie, have increased by an estimated 50 percent in recent years, experts say. But many doctors are puzzled because the operation doesn't carry a 100 percent guarantee, it's major surgery -- and women have other options, from a once-a-day pill to careful monitoring.

The report by Texas universities and government agencies cites high poverty and low education along the Mexican border as major contributing factors. The authors said the study is among the first to focus on nutrition-related diseases in a primarily Mexican-American region.

“They are the poorest of the poor,” said Sue Day, editor of the study and associate professor of epidemiology and nutrition at The University of Texas School of Public Health at Houston. “They are at the bottom of most of the health and economic lists.”

Of the estimated 1 million people in the Rio Grande, many are Mexican immigrants living below the federal poverty level. About one-third of residents over 25 do not have a ninth-grade education, according to the study. The national average is 5 percent.

“Persons who aren’t as educated have a harder time getting jobs which have good salaries to engage in better health care, good nutrition,” Day said.

Poor nutrition and health carePoor nutrition also makes people more prone to infectious disease, birth defects and cancer. The study found that fact to be compounded by a lack of medical care in the Valley, where two of the counties have no gynecologists or obstetricians.

The high cervical cancer rate is an indication of the area’s lack of proper nutrition and health care.

Women typically are routinely screened for the virus that causes most cervical cancer and cell abnormalities that can be treated in the pre-cancer stages. Poorly nourished women are more susceptible to the virus, and low-income women in the Valley are likely to see a doctor only after the disease has progressed, the study found.

The study did include some good news. Rates of breast, prostate, and colorectal cancer are lower, as are rates of low birth-weight infants.

But weight problems are prevalent, contributing to diabetes and heart disease. While about 25 percent of Texas boys are overweight, the rate is about 33 percent in Hidalgo County, according to the study. That is the highest rate in the nation, according to state and federal health data.